so normally power goes in runs through the mac and a part of it goes out the USB ports. The power normally charging your laptop is the exact same juice that comes out of the USB ports to power any peripheral devices. It does not matter if the power is slightly less passing through your USB-C port. This is why it's not recommended by apple I guess. This will indeed charge the computer, untill you ask for more juice (gaming, heavy workloads and the lot) then you will put a lot of pressure on your 60 watt magsafe to produce more that what it is rated at potentially harming it or the mac. 'With that said, I've used my wife's 60 watt power adaptor with my MacBook Pro (15'), and even though it's lower than the recommend 87 watts, it does charge the computer.' The 'con' of not using the full 87-watt source is that it will simply not charge the battery as quickly. Running your computer at a lower wattage seems to be very common and typically not unsafe IF you use quality cables and chargers. I have no idea what the true engineering minimum spec for a 15-inch MPB is. I sometimes use the 13-inch MBP, 60-watt charger for travel use because it is smaller and lighter. I typically use a USB hub which only passes through 49 watts as you can see from my screenshot below. In my experience, if you have a genuine Apple 87W USB-C power adapter connected you will see the wattage displayed at 86 (On 15-inch MBP). The AC Charger Information will tell you exactly the current status of the AC power supply. On the right side, Scroll Down until you see ' AC Charger Information.'

On the left side of the Hardware list, select ' Power.'Ĥ. Click on small apple icon on the top left of your screen and then select ' About This Mac.'ģ. To see what power wattage the computer is actually receiving:ġ.

2015 macbook pro charger wattage